Adhesion of rubbery polymers to fibrous materials



Jan. 17, 1961 F. P. BALDWIN ETAL 2,968,587 ADHESION 0F RUBBERY POLYMERST0 FIBROUS MATERIALS Filed Dec. 19, 1955 Inventors Samuel B. RobisonFrancis P Baldwin By lifi M Attorney Unite States ADHESION OF RUBBERYPOLYMERS T FIBROUS MATERIALS Francis P. Baldwin, Colo'nia, and Samuel B.Robison,

Roselle, N.J., assignors to Esso Research and Eng:- neering Company, acorporation of Delaware Filed Dec. 19, 1955, Ser. No. 553,829

'15 Claims. (Cl. 154-139) This invention relates to coating compositionsfor natural or synthetic fibrous materials, such as cotton, rayon,nylon, etc., to improve the adhesion thereof to rubber such as naturalrubber or especially synthetic rubber such as GR-S rubber, Buna-Nrubber, and preferably butyl rubber.

More particularly, the present invention relates to coating compositionscontaining chlorinated butyl rubber. The invention also involvesprocesses for producing the aforesaid compositions and to methods ofemploying the same to obtain improved adhesion between a rubber andfibrous filaments, cords, threads, fabrics, etc. particularly in thepresence of phenolic-aldehyde resins. The present invention alsoappertains to the resulting rubberfibrous composites produced by theaforesaid processes.

Heretofore, cellulosic and synthetic fibers such as rayon, regeneratedcellulose and nylon threads, cords, or filaments have adhered verypoorly to rubber and to compounded rubber stocks (especially containingbutyl rubber) when they were united and the rubber stock subsequentlycured according to any known process of producing adhesion betweenrubber and fibers. This poor adhesion, especially of synthetic threads,cords, and fabrics to synthetic rubber such as butyl rubber hasconstituted a very serious obstacle to more extensive use of butylrubber in the manufacture of automobile tires, reinforced rubber beltsand similar products consisting of alternate plies of rubber and cords.Such products are required to adhere very strongly for long periods oftime under drastic conditions of high temperature, constant flexing,bending, shock, etc. For exampel, if nylon cord is pressed into butylrubber or a butyl rubber stock and the composite vulcanized, it will beobserved that the nylon cord may be pulled away from the rubber withcomparative facility.

Butyl rubber comprises a copolymer containing about iii-99.5%,preferably 9599.5% of a C -C iso-olefin such as isobutylene, theremainder being a C -C multiolefin, preferably a C, to C conjugateddiolefin such as butad ene, dimethyl butadiene, piperylene or especiallyisoprene. The preparation of butyl-type rubbers is described in Us.Patent 2,356,128 to Thomas et al. and also in other patents as well asin literature.

According to the present invention, fibrous materials such as tire cordsare coatedwith a phenolic-aldehyde type resin and a chlorinated butylrubber which contains at least 0.5, preferably at least 1.0 weightpercent combined chlorine but not more than about X weight percentcombined chlorine wherein 35.'46=atomic weight of chlorine.

2,968,587 Patented Jan. 3?, 1961 The invention will be more apparentwith reference to the drawing in which the single figure is across-sectional view of a pneumatic tubeless tire depicted as beingmounted on a conventional tubeless type of tire wheel ILll'l.

In one embodiment of the present invention, fibrous materials such astire cords are first passed through an aqueous solution of aphenolic-aldehyde type resin such as a resorcinol-formaldehyde resin,having a mole ratio of the phenolic compound to the aldehyde of about1-1 to about l5, and dried. The concentration of the resin in theaqueous solution is preferably between about 0.5% to 10%.

The resulting resin-coated cord is then dipped into a solution ofchlorinated butyl rubber cement, or preferably calendered at betweenabout F. to 275 F. with a chlorinated butyl rubber composition in which100 parts by weight of the chlorinated butyl rubber have been compoundedto form a composition comprising:

The chlorinated butyl rubber cement preferably contains about 5 to 50grams of the above composition plus chlorinated butyl rubber dissolvedin about 50-200 cc. of a rubber solvent such as kerosene, naphtha,straight run mineral spirits, gasoline, hexane, heptane, benzene,toluene, ethyl chloride, chloroform, carbon tetrachloride, carbondisulfide, etc.

The cords, treated as above-described, are then dried at temperaturesabove about F., preferably above 200 F., e.g. 225 F. The cords may thenbe embedded in an unvulcanized rubber such as butyl rubber, naturalrubber, chlorinated butyl rubber, GR-S rubber (a rubberybutadiene-styrene copolymer), Buna-N rubber (a rubberybutadiene-acrylonitrile copolymer), chloroprene rubber, etc., andsulfur-vulcanized at 250 to 400 F, preferably 280 to 370 F. for aboutone minute up to several hours or more to produce a finished articlehaving an improved bond between the coated cords and the rubber.

The above procedure produces superior articles suitable for use inconstructing tire carcasses for autos, trucks, airplanes, etc. as wellas numerous other uses such as conveyor belts and other products builtup of a plurality of laminations of cord and a rubber such as butylrubber; the invention being especially applicable to such products whichhave at least one layer which is of butyl rubber. The invention may alsobe applied in uses involving merely a single layer of a fabric such asnylon, cotton, rayon, silk, etc., which may be either coated on one sideor both sides, with the resin and chlorinated butyl rubber as describedabove.

The cure of the finished articles may be: not only in the presence ofsulfur or sulfur-containing vulcanization agents, but also by the use ofpd inltrosobenzene, p-quinone dioxime, p-quinone dioxime dibenzoate,tellurium diethyl dithiocarbamate, polyalkyl thiuram sulfides such astetramethyl thiuram disulfide, etc. The cure is also preferably in thepresence of basic metal compounds such a bivalent metal oxides, e.g.zinc oxide.

The phenolic-aldehyde resins which are within the purview of the presentinvention may be generally defined as belonging to the class ofheat-hardening phenolaldehyde type resins, preferably resins fromphenolic compounds which, prior to heat-hardening or thermosetting arewater soluble at least to the extent of 5-10% -or more. Such resins arecapable of thermally setting in the absence of any added catalysts attemperatures of about 150-400 F., temperatures of 200-300 F. be ingpreferred for coating rayon whereas higher temperatures are permissiblefor nylon.

As phenolic compounds capable of producing resins of the abovementionedcharacteristics, mono or especially dihydroxy benzenes are satisfactory.Di-hydroxy benzenes having the hydroxyl groups meta with respect to eachother are preferred. Satisfactory phenolic compounds include phenol,cresols, phloroglucino'l, xylenols, trimethyl phenols, mono or dichlorophenols, diamyl or diisopropyl phenols, p-tertiary butyl phenol,p-phenylphenol, hydroquinone, and especially resorcinol.

The preferred aldehydes for reaction with the above phenolic compoundsare formaldehyde or materials supplying formaldehyde such asparaformaldehyde. Other suitable aldehydes include acetaldehyde,propionaldehyde, furfural, etc. The ratio of the phenolic compound tothe aldehyde is preferably such that the resin, prior to thermosetting,has substantial water solubility as well as solubility in polarsolvents. In order to produce the desired resin, a small amount of analkali metal containing catalyst or other condensing agent is preferred.If sodium hydroxide is employed, it is advantageously present in amountsof about 0.02 to 0.5 percent by Weight, based on reactants.

The chlorinated butyl rubber is produced by reacting the unvulcanizedrubber with chlorine or chlorine-containing compounds so that thepolymer contains at least 0.5 weight percent of combined chlorine butnot more than about 1 atom of chlorine combined in the polymer permolecule of multi-olefin present therein; i.e. not more than about oneatom of combined chlorine per double bond in the polymer. In otherwords, the maximum mole percent of combined chlorine should be about0.25-0.60 times the mole percent unsaturation of the polymer asdetermined by the Iodine-Mercuric Acetate Method (Gallo, Wiese andNelson, Industrial Engineering Chemistry, volume 40, page 1277; (1948).

Suitable chlorinating agents which may be employed are molecularchlorine, alkali metal hypochlorites (preferably sodium hypochlorite),sulfur chlorides (particularly oxygenated sulfur chlorides), pyridiniumchloride perchloride, N-chlorcsuccinimide, alpha-chloroacetoacetanilide,trichlorophenol chloride, N-chloroacetamide, beta-chloromethylphthalimide, and other common chlorinating agents. The preferredchlorinating agents are molecular chlorine and sulfuryl chloride. Thechlorination is advantageously conducted at 0 to 100 C. and preferablyat about 20 to 80 C. for about one minute to several hours. However, thetemperatures and times are regulated to chlorinate the rubbery copolymerto the extent abovementioned.

The chlorination may be accomplished in various ways. One processcomprises preparing a solution of the co polymer in a suitable inertliquid organic solvent such as an inert hydrocarbon or advantageouslyhalogenated derivatives of saturated hydrocarbons, examples of which arehexane, heptane, naphtha, kerosene, straight run mineral spirits,benzene, toluene, naphthalene, chlorobenzene, chloroform,trichloroethane, carbon tetrachloride, etc., and adding thereto thechlorine or other chlorinating agent, preferably in solution, such asdissolved in an alkyl chloride, carbon tetrachloride, etc. Othervariations, which are not as preferred, comprise employing thechlorinating agent in the form of a gas, and contacting the gas witheither a solution of the butyl copolymer or the solid copolymer per so.For example, if elemental chlorine is employed, it may be advantageouslyadded directly to the solution of butyl copolymer. The

use of elevated or depressed pressures is optional since atmosphericpressure is satisfactory although the pressure may vary from about 1 to400 p.s.i. depending upon the foregoing temperatures and time ofreaction.

The copolymer to be chlorinated is advantageously first dissolved in asolvent such as any of the foregoing, especially a saturated hydrocarbonor benzene or a completely chlorinated hydrocarbon. Particularlypreferred solvents for particular chlorinated agents are as follows:carbon tetrachloride and/ or chloroform and/ or benzene and/or lowboiling paraflinic hydrocarbons (c.g. hexane) for molecular chlorine;paraffinic hydrocarbons and/or carbon tetrachloride and/or aromaticssuch as benzene as non-polar solvents for chlorination with certainchlorinating agents, especially sulfuryl chloride. However, any of theabove-listed ch'lorinating agents may be employed with an inert polarsolvent for the copolymers providing the conditions of chlorination andamounts of the chlorinating agent are carefully controlled.

The invention will be better understood from the following experimentaldata and examples.

Chlorinated butyl rubber-A: Sixty grams of butyl rubber (GR-l-lS) weredissolved in 960 grams of carbon tetrachloride. This solution was thensaturated with sulfur dioxide (which is an optional step). Eighteenmilliliters of liquid sulfuryl chloride were then added and reaction wasallowed to ensue for one hour at room temperature. The chlorinatedrubbery polymer formed was then precipitated by the addition of excessisopropyl alcohol. In place of isopropyl alcohol, other knownnonsolvents for butyl rubber may be employed such as C -C alkanols,ketones such as acetone etc. The rubbery polymer was then redissolved inhexane and reprecipitated with isopropyl alcohol. The chlorinatedrubbery product was dried at 65 C. under a vacuum of 0.1-2.0 inches ofmercury absolute. The chlorinated product compared to the originalpolymer as follows:

Iodine no. (cg/g) =11.6 Iadine no. (cg/g) =4.87

0.8 wt. percent combined chlorine.

' rubber-B was repeated except that the unchlorinated butyl rubber wasGR-I-ZS.

Chlorinated butyl rubberD: The same general procedure as in thepreparation of chlorinated butyl rubber--B was repeated except that theGR-I-15 was dissolved in 300 cc. of n-heptane instead of carbontetrachloride.

Example I Component; Parts by Weight Chlorinated butyl rubber"A Pigment(EPC carbwn black) 5O Mold release agent (stearic acid) 1.0 Anti-O idaut(phenyl beta naphthylamine) 0. 25 Zinc Oxide 5.0

Rayon and nylon tire cords were first treated with aqueous solutions ofresorcinol-formaldehyde resins having mole ratios of formaldehyde toresorcinol of Hi to 5/1 as tabulated below. The condensation between theresorcinol and the formaldehyde was at 25 C. for 48 hours. The resinconcentrationwas 5 parts by weight of resin per 100 parts by weight ofwater. The cords were placed beneath the surface of the resin solution,which had been aged for 48 hours at room temperature and maintained in abeaker, by a wire guide. The time of aging may be almost negligible upto about one month or more at room temperature up to about 200 F. Thecord was, then dried in a circulating air oven at 250 F. for 5 minutes.

The above chlorinated butyl rubber cement was then applied by forcingthe resin-coated cords beneath the surface of the cement by a wire guideand then passed through an air blast to remove excess cement. The cordwas then redried for 5 minutes at 250 F.

The cords were then embedded in an uncured butyl rubber matrix andvulucanized for 25 minutes at 320 F.; the matrix having the followingcomposition:

1 The pla tici er hydrocarbon oil was a paratfinic base oil having thefollowing characteristics:

S.S.U. at 100 F l1" Pour Point, F 3 Flash Point, F 65 The adhesions ofthe cords, coated in accordance with the invention. to the matrix weremeasured by a tech nique essentially similar to the H test described byLyons, Conrad and Nelson, Rubber Chemistry and Technology, 268, vol. XX(1947), except that the test speciments were prepared with a /2 inchlength of treated cord being vulcanized into the center of the 1 /2 x /2x A inch butyl rubber matrix composition. The tire cords used were rayontire cord of 1650 denier, 2 ply construction and nylon cord of 840denier, 2 ply construction. The vulcanized rubber matrix was reinforcedwith light cotton duck on the two long sides from which the cord did notprotrude. The force required to pull the /2 inch length of cord from therubber block was measured by means of a Scott tensile tester at a 20inches per minute jaw separation rate. The results were as follows:

Cord Rayon ylon Cord 1t 1 2 3 4 5 Mole ratios (fornaldchytle/rcsorcinol)1!] 3/1 4/1 5 1 3/1 Resorcinol. g 1. 6 6 5 5 6 37% formaldehyde, 0 4.012.2 13.6 16.9 12. 2 I\'aOH. 1%, cc 12 12 10 10 12 Water, cc 130 187 179205 187 H 'lcst Adhesion Results (Adhesion in pflilldS at room temperatime) 21.1 17. 4 18.3 20. 6 14.6

Chlorinated butyl rubbers B, C, and ,D were compounded on a rubber millto produce cement formulations containing 130 cc. of heptane and 15grams of the following:

Component Parts by Weight Chlorinated paly ner MP0 carbon black..- 50Stearie acid 1.0 Phenyl beta naphthylanine.-. 0.25 Zinc oxide 5.0

Cord Rayon Nylon Card 6 7 8 Chliri uteri iu'yl ttub ver .1 B C D Ad 1e.ion (pm ids at ro rm to r 18.1 19.1 18.7

The above data indicate the superior adhesion of rubber to cords 6, 7,and 8 coated in accordance with the invention; maximum adhesion valuesobtainable heretofore for rayon being l3-l5 pounds and for nylon being5-7 pounds.

Example III The same general procedure as in Example 11, cord No. 7 wasrepeated, except that the chlorinated butyl rubber cement contained noanti-oxidant and no zinc oxide, the cement containing cc. of n-heptaneand 15 grams of the same proportions of chlorinated butyl rubber- C,stearic acid and M.P.C. carbon black.

The adhesion value obtained, under the identical testing conditions was18.8 pounds. This value is considerably above the usual 13-15 poundsadhesion according to the prior known methods employing unmodified butylrubber cements. It is also evident that the curative zinc oxide is notneeded to obtain excellent adhesion. This is most surprising since butylrubber formulations heretofore have invariably required the presence ofa bivalent metal oxide such as zinc oxide in order to producevulcanizates of any appreciable adhesion to tire cords.

One particular advantageous use for the chlorinated butylrubber-phenolic aldehyde resin combinations of the present invention isin pneumatic tires of either the inner tube containing variety or in atubeless type tire. Referring now to the drawing, the single figuredepicts a pneumatic tubeless tire which comprises a hollow toroidal typemember which is substantially U-shaped in crosssection by virture of anopen portion which extends around the inner periphery of the member. Inother words, the tire is of a tubular type structure which has a crosssection in the form of an open-bellied body with spaced terminalportions to define a member generally resembling a horseshoe. Theterminal portions constitute the bead portions 11-11 of the tire insideof which are a plurality of bead wires adhesively imbedded and molded ina rubber. The outer surface of the head portion is advantageously formedinto an air sealing means, such as a plurality of ribs to aid inadhesion to rim. 12 when the tire is inflated.

The outer surface of the tire also includes tread area 13 and sidewalls14. The open portion of the horseshoeshaped tire faces that portion ofthe inner circumference of the tire which is adjacent the said treadarea 13 of the tire. The remaining construction of the tire may varyaccording to conventional fabrication, but in general the tire is amulti-layered type of structure with an outer layer as above-mentioned.The layer next adjacent the outer layer generally comprises a carcass 15which includes a rubber having incorporated therein a fabric composed ofa plurality of cotton, rayon or nylon cords.

According to one embodiment of the present invention, said automobiletire cords are coated first with an aqueous solution of a resinousphenolic-aldehyde condensation product, preferablyresorcinol-formaldehyde, and then coated with a cement comprising asolution of chlorinated butyl rubber in a volatile solvent. The butylrubber contains at least 0.5 wt. percent combined chlorine but not morethan about one combined atom of chlorine per double bond in the polymer.The cement also may contain a rubber pigment (filler) such as carbonblack, clays, silica, etc.; bivalent metal oxides (or hydroxides) suchas ZnO, CaO, MgO; plasticizer oils; ultra accelerators and/ oranti-oxidants etc. The resulting coated cord when dried has been foundto have much greater adhesion after vulcanization at 250400 F. to butylrubber and other rubbers in the carcass layers of tires.

The tire also includes an inner lining advantageously made from rubber,e.g. butyl rubber or chlorinated butyl rubber, which must besubstantially impermeable to air. For example, the lining mayadvantageously comprise natural rubber, a rubbery copolymer, chlorinatedcopolymer or mixtures of any of the above wherein the copolymercomprises the reaction product of about 70-995 weight percent of a C -Cisoolefin, such as isobutylene, and about 0.5-30 weight percent of a C-C multi-olefin, such as isoprene which has been at least partiallyvulcanized by heating in the presence of a vulcanization agent forseveral minutes to hours at 200400 F. The above multi-layers, at leastthree in number, are conventionally bonded or otherwise adheredtogether, for example, by cementing and/or especially by vulcanization,etc., to form a tire of a unitary structure.

The chlorinated butyl rubber and phenolic-aldehyde compositions of thepresent invention may be employed in the tire carcass alone or inadmixture with minor proportions of natural rubber or certain syntheticrubbers to include chloroprene rubber, polyisoprene, butadiene orisoprene vinyl pyridine copolymers, and particularly copolymers ofbutadiene with acrylonitrile (e.g. Buna-N rubber) or copolymers ofbutadiene with styrene such as GRS rubber, etc.

An intermediate or carcass layer including a rubber and a plurality offibrous cords and/or fabric, must be of both desirable rigidity andstrength. The performance of this layer is therefore dependent upon thebond or adhesion between the cords or fabric and the rubber. Certainsynthetic rubbers, and especially butyl rubber does not normally havegood adhesion to such fibrous materials, particularly if they aresynthetic such as rayon, polyacrylonitrile and especially nylon. Thepresent invention has solved this difiiculty and provides a strong bondbetween butyl rubber and such fibers by employing the coatingcompositions and coating technique as hereinbefore described.

While there are above described a number of specific embodiments of thepresent invention, it is obviously possible to produce other embodimentsand various equivalent modifications and variations thereof withoutdeparting from the spirit of the invention or the scope of the appendedclaims.

What is claimed is:

1. A process for improving the surface tack of a textile fibrousmaterial which comprises coating said material with a first layer of aphenolic-aldehyde resin and a second layer of a butyl rubberisoolefin-multiolefin copolymer modified to contain at least 0.5 wt. ofchlorine to improve its adhesive characteristics, but not more thanabout one combined atom of chlorine per double bond in the butyl rubber.

2. Process according to claim 1 in which the phenolicaldehyde resin is aresorcinol-formaldehyde resin.

3. Process according to claim 1 in which the chlori nated butyl rubbercopolymer formed is also in admixture with per parts of said rubberabout:

10-100 parts by weight of carbon black and 5-20 parts by weight of zincoxide.

4. A process which comprises coating fibrous textile materials with anaqueous solution of a phenolic-aldehyde resin, drying said material andcoating the product formed with a chlorinated isoolefin-multiolefinbutyl rubber copolymer-containing cement in which'the butyl rubbercopolymer has been reacted with at least about 0.5 weight percentchlorine but not more than about 1 atom of combined chlorine per doublebond in the copolymer.

5. Process according to claim 4 in which the fibrous material is asynthetic tire cord, the resin being a resorcinol-formaldehydecondensation product.

6. Process according to claim 5 in which the tire cords are of nylon.

' 7. Process according to claim 4 in which the butyl rubber copolymer isdissolved in a volatile organic solvent.

8. A textile fibrous material coated with a first layer of aphenolic-aldehyde resin and a second layer of a butyl rubberisoolefin-multiolefin copolymer modified to contain at least 0.5 wt. ofchlorine to improve its adhesion characteristics but not more than aboutone atom of combined chlorine per double bond in the rubber.

9. A textile fibrous material coated with a first layer of aresorcinol-formaldehyde resin and having an outer coating of a cement ofa butyl rubber isoolefin-multiolefin copolymer modified with at least0.5 wt. percent of chlorine to improve its adhesion characteristics, butnot more than about one atom of combined chlorine per double bond in therubber.

10. A laminated structure comprising a textile fibrous material, saidfibrous material being coated with a first layer of aresorcinol-formaldehyde type resin and a second layer of a butyl rubberisoolefin-multiolefin copolymer modified to contain at least about 0.5wt. percent chlorine but not more than about one combined atom ofchlorine per double bond in the polymer, and at least one layer of anunmodified butyl rubber isoolefin-multiolefin copolymer adhesivelyunited thereto.

11. A rubber tire which contains in the carcass thereof a plurality ofcords imbedded in a rubber, said cords having been coated with aphenolic-aldehyde resin and a multiolefin-isoolefin butyl rubbercopolymer which has been modified to contain at least 0.5 wt. percent ofchlorine to improve the adhesion of said cords to the rubberin whichthey are imbedded, but not more than about one atom of chlorine perdouble bond in the rubber.

12. In a tubeless tire, the combination which comprises an inner layerof a member selected from the group consisting of natural rubber, anisoolefin-multiolefin butyl rubber copolymer and a chlorinatedisoolefin-multiolefin butyl rubber copolymer; an outer layer includingan openbellied body comprising two opposing sidewalls, spaced beadportions and a median tread area; and an intermediate layer defining acarcass including an unmodified isoolefin-multiolefin butyl rubbercopolymer and a plurality of cords imbedded therein, wherein said cordshave been first coated with a water-soluble phenolic-aldehyde resin andthen coated with a multiolefin-isoolefin butyl rubber copolymer modifiedto contain at least 0.5 wt. percent of chlorine to improve the adhesionof said cords to the unmodified butyl rubber but not more than about onecombined atom of chlorine per double bond in the rubber.

13. A fibrous material selected from the group of rayon and nylon,coated with a first layer of a resorcinol-formaldehyde resin and asecond layer of an isobutylene-isoprene butyl rubber copolymer having aniodine number of about 11 modified to contain about 0.8 wt. percent ofchlorine.

14. An article according to claim 13, said chlorinated butyl rubbercopolymer having been chlorinated at about 20-80 C.

15. A process which comprises coating a fibrous material selected fromthe group of rayon and nylon with an aqueous solution of aresorcinol-formaldehyde resin, drying said material and coating thedried product with a chlorinated butyl rubber cement in which the butylrubber is an isobutylene-isoprene butyl rubber copolymer having aniodine number of about 11, modified by reaction with sulfuryl chlorideat about 2080 C. to incorporate about 0.8 wt. percent chlorine, toimpart improved adhesive characteristics thereto when imbedded entirelyin an unmodified isoolefin-multiolefin butyl rubber copoly mer.

References Cited in the file of this patent UNITED STATES PATENTS Churchet al. Aug. 30, 1938 Hershberger Aug. 20, 1940 Briant July 25, 1944 Hallet al. May'25, 1948 Gentle et a1 Sept. 29, 1953 Perkins Dec. 28, 1954Crawford et a1 Oct. 11, 1955 Morrissey et a1 Ian. 24, 1956 Buckwalter etal. May 22, 1956 Robison July 10, 1956 Rowe et a1 Feb. 4, 1958

10. A LAMINATED STRUCTURE COMPRISING A TEXTILE FIBROUS MATERIAL, SAIDFIBROUS MATEIRAL BEING COATED WITH A FIRST LAYER OF ARESORCINOL-FORMALDEHYDE TYPE RESIN AND A SECOND LAYER OF A BUTYL RUBBERISOOLEFIN-MULTIOLEFIN COPOLYMER MODIFIED TO CONTAIN AT LEAST ABOUT 0.5WT. PERCENT CHLORINE BUT NOT MORE THAN ABOUT ONE COMBINED ATOM OFCHLORINE PER DOUBLE BOND IN THE POLYMER, AND AT LEAST ONE LAYER OF ANUNMODIFIED BUTYL RUBBER ISOOLEFIN-MULTIOLEFIN COPOLYMER ADHESIVELYUNITED THERETO.